find one person to walk/ride with. Then you are accountable to that person for showing up every day (or whatever your agreed schedule)
+1
Also, as mentioned before, have your Doc check you out. I was like this (and sometimes still am), and came to find out I have Hypothyroidism. Basically, without taking my meds, I contemplate, "Do I REALLY need to get off the couch to go pee, or can I hold it another hour?"
On the meds, not only do I pee when I need to, but I get off the couch for other reasons... like when I am thirsty, I no longer wait for someone else to get up, so I can ask THEM to get it for me.